Fine-fraction carbonate stable isotopes as indicators of seasonal shallow mixed-layer paleohydrography

Atsuhito Ennyu, Michael A. Arthur, Mark Pagani

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We have measured stable isotopic compositions of Miocene pelagic fine-fraction (< 63 μm) carbonates from oligotrophic deep-sea sites in the Pacific and Atlantic oceans and compared them with those of coexisting foraminifers to test their utility as near sea-surface indicators. Fine-fraction carbonates (primarily polyspecific nannofossils) and surface-dwelling planktic foraminiferal (Globigerinoides) stable isotopes both have been considered to reflect surface-water hydrographic conditions. However, our results indicate that fine-fraction stable isotopes are offset from and do not correlate well with those of Globigerinoides. In contrast, stable isotopic records of the deep-dwelling planktic foraminifer Globoquadrina are in good correspondence with the fine-fraction records in terms of long-term (ca. > 1 m.y.) trends and temporal variability. On the basis of a time-series hydrography and flux study site in the oligotrophic subtropical North Atlantic, we interpret the isotopic discrepancies between fine-fraction and Globigerinoides as resulting primarily from season of calcification, as well as possible vital effects. We suggest that fine-fraction stable isotope values from oligotrophic waters reflect late winter-early spring relatively cool, nutrient-rich shallow mixed-layer conditions during the time of deep mixing (i.e., spring bloom), whereas Globigerinoides stable isotope values record conditions that prevailed in the stratified surface waters in the warmer late spring-fall. This implies that paired analyses of fine-fraction anal surface-dwelling planktic foraminiferal-δ18O could be applied to reconstruct paleoseasonality of the open oceans. However, because the fine-fraction δ13C values are not representative of the annual mean surface-water δ13C, we recommend use of near surface-dwelling planktic foraminiferal δ13C as a proxy for δ13C of stratified surface waters that are more or less in equilibrium with the atmosphere with respect to pCO2.

Original languageEnglish (US)
Pages (from-to)317-342
Number of pages26
JournalMarine Micropaleontology
Volume46
Issue number3-4
DOIs
StatePublished - Nov 1 2002

Fingerprint

mixed layer
stable isotope
carbonate
surface water
calcification
hydrography
open ocean
algal bloom
isotopic composition
Miocene
indicator
time series
atmosphere
nutrient
winter
water
dwelling

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Palaeontology

Cite this

Ennyu, Atsuhito ; Arthur, Michael A. ; Pagani, Mark. / Fine-fraction carbonate stable isotopes as indicators of seasonal shallow mixed-layer paleohydrography. In: Marine Micropaleontology. 2002 ; Vol. 46, No. 3-4. pp. 317-342.
@article{fa68a66637ca49c4a8f0ed62d17e2b7d,
title = "Fine-fraction carbonate stable isotopes as indicators of seasonal shallow mixed-layer paleohydrography",
abstract = "We have measured stable isotopic compositions of Miocene pelagic fine-fraction (< 63 μm) carbonates from oligotrophic deep-sea sites in the Pacific and Atlantic oceans and compared them with those of coexisting foraminifers to test their utility as near sea-surface indicators. Fine-fraction carbonates (primarily polyspecific nannofossils) and surface-dwelling planktic foraminiferal (Globigerinoides) stable isotopes both have been considered to reflect surface-water hydrographic conditions. However, our results indicate that fine-fraction stable isotopes are offset from and do not correlate well with those of Globigerinoides. In contrast, stable isotopic records of the deep-dwelling planktic foraminifer Globoquadrina are in good correspondence with the fine-fraction records in terms of long-term (ca. > 1 m.y.) trends and temporal variability. On the basis of a time-series hydrography and flux study site in the oligotrophic subtropical North Atlantic, we interpret the isotopic discrepancies between fine-fraction and Globigerinoides as resulting primarily from season of calcification, as well as possible vital effects. We suggest that fine-fraction stable isotope values from oligotrophic waters reflect late winter-early spring relatively cool, nutrient-rich shallow mixed-layer conditions during the time of deep mixing (i.e., spring bloom), whereas Globigerinoides stable isotope values record conditions that prevailed in the stratified surface waters in the warmer late spring-fall. This implies that paired analyses of fine-fraction anal surface-dwelling planktic foraminiferal-δ18O could be applied to reconstruct paleoseasonality of the open oceans. However, because the fine-fraction δ13C values are not representative of the annual mean surface-water δ13C, we recommend use of near surface-dwelling planktic foraminiferal δ13C as a proxy for δ13C of stratified surface waters that are more or less in equilibrium with the atmosphere with respect to pCO2.",
author = "Atsuhito Ennyu and Arthur, {Michael A.} and Mark Pagani",
year = "2002",
month = "11",
day = "1",
doi = "10.1016/S0377-8398(02)00079-8",
language = "English (US)",
volume = "46",
pages = "317--342",
journal = "Marine Micropaleontology",
issn = "0377-8398",
publisher = "Elsevier",
number = "3-4",

}

Fine-fraction carbonate stable isotopes as indicators of seasonal shallow mixed-layer paleohydrography. / Ennyu, Atsuhito; Arthur, Michael A.; Pagani, Mark.

In: Marine Micropaleontology, Vol. 46, No. 3-4, 01.11.2002, p. 317-342.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Fine-fraction carbonate stable isotopes as indicators of seasonal shallow mixed-layer paleohydrography

AU - Ennyu, Atsuhito

AU - Arthur, Michael A.

AU - Pagani, Mark

PY - 2002/11/1

Y1 - 2002/11/1

N2 - We have measured stable isotopic compositions of Miocene pelagic fine-fraction (< 63 μm) carbonates from oligotrophic deep-sea sites in the Pacific and Atlantic oceans and compared them with those of coexisting foraminifers to test their utility as near sea-surface indicators. Fine-fraction carbonates (primarily polyspecific nannofossils) and surface-dwelling planktic foraminiferal (Globigerinoides) stable isotopes both have been considered to reflect surface-water hydrographic conditions. However, our results indicate that fine-fraction stable isotopes are offset from and do not correlate well with those of Globigerinoides. In contrast, stable isotopic records of the deep-dwelling planktic foraminifer Globoquadrina are in good correspondence with the fine-fraction records in terms of long-term (ca. > 1 m.y.) trends and temporal variability. On the basis of a time-series hydrography and flux study site in the oligotrophic subtropical North Atlantic, we interpret the isotopic discrepancies between fine-fraction and Globigerinoides as resulting primarily from season of calcification, as well as possible vital effects. We suggest that fine-fraction stable isotope values from oligotrophic waters reflect late winter-early spring relatively cool, nutrient-rich shallow mixed-layer conditions during the time of deep mixing (i.e., spring bloom), whereas Globigerinoides stable isotope values record conditions that prevailed in the stratified surface waters in the warmer late spring-fall. This implies that paired analyses of fine-fraction anal surface-dwelling planktic foraminiferal-δ18O could be applied to reconstruct paleoseasonality of the open oceans. However, because the fine-fraction δ13C values are not representative of the annual mean surface-water δ13C, we recommend use of near surface-dwelling planktic foraminiferal δ13C as a proxy for δ13C of stratified surface waters that are more or less in equilibrium with the atmosphere with respect to pCO2.

AB - We have measured stable isotopic compositions of Miocene pelagic fine-fraction (< 63 μm) carbonates from oligotrophic deep-sea sites in the Pacific and Atlantic oceans and compared them with those of coexisting foraminifers to test their utility as near sea-surface indicators. Fine-fraction carbonates (primarily polyspecific nannofossils) and surface-dwelling planktic foraminiferal (Globigerinoides) stable isotopes both have been considered to reflect surface-water hydrographic conditions. However, our results indicate that fine-fraction stable isotopes are offset from and do not correlate well with those of Globigerinoides. In contrast, stable isotopic records of the deep-dwelling planktic foraminifer Globoquadrina are in good correspondence with the fine-fraction records in terms of long-term (ca. > 1 m.y.) trends and temporal variability. On the basis of a time-series hydrography and flux study site in the oligotrophic subtropical North Atlantic, we interpret the isotopic discrepancies between fine-fraction and Globigerinoides as resulting primarily from season of calcification, as well as possible vital effects. We suggest that fine-fraction stable isotope values from oligotrophic waters reflect late winter-early spring relatively cool, nutrient-rich shallow mixed-layer conditions during the time of deep mixing (i.e., spring bloom), whereas Globigerinoides stable isotope values record conditions that prevailed in the stratified surface waters in the warmer late spring-fall. This implies that paired analyses of fine-fraction anal surface-dwelling planktic foraminiferal-δ18O could be applied to reconstruct paleoseasonality of the open oceans. However, because the fine-fraction δ13C values are not representative of the annual mean surface-water δ13C, we recommend use of near surface-dwelling planktic foraminiferal δ13C as a proxy for δ13C of stratified surface waters that are more or less in equilibrium with the atmosphere with respect to pCO2.

UR - http://www.scopus.com/inward/record.url?scp=0036842633&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036842633&partnerID=8YFLogxK

U2 - 10.1016/S0377-8398(02)00079-8

DO - 10.1016/S0377-8398(02)00079-8

M3 - Article

AN - SCOPUS:0036842633

VL - 46

SP - 317

EP - 342

JO - Marine Micropaleontology

JF - Marine Micropaleontology

SN - 0377-8398

IS - 3-4

ER -